Quality control is a constant concern in the manufacturing industry. Therefore, numerous tools have been developed over time to assist operators in performing inspection of manufactured objects at different stages of the manufacturing process.
For example, several systems and corresponding methods of operation are known in the art to perform computerized dimensional and visual inspection of an object. Such systems typically capture object data relative to the object for subsequent processing by the system and visualisation by a user. Typically, inspection data generated by processing of the captured object data is visualized either on a display screen of a computer, using a three dimensional visualisation software where the inspected object, along with the inspection information overlaid on the object, can be rotated and inspected, or on a printout where specific viewpoints showing the inspected object and inspection information are presented.
Known systems however tend to suffer from several drawbacks. In particular, the visualisation of the inspected object and inspection information on a display screen or a printout copy with specific viewpoints can lead to misconceptions between what is displayed on the screen or printout and the corresponding regions of the inspected object. For example, and without being limitative, in a case where a specific region of the inspected object is targeted as needing to be reworked, an erroneous interpretation of the relationship between the displayed information and the physical object which is inspected can lead to faulty identification of the targeted region of the object. In other words, an operator can confuse the targeted region with another region of the inspected object and consequently proceed to rework the wrong region. Such misconceptions are especially likely to occur in cases where the object is symmetrical and can lead to the original defect remaining uncorrected and still be present on the final object. Such misconceptions can be costly, time consuming and potentially dangerous if the region that was not properly reworked is critical.
The applicant is also aware of inspection systems where video-projectors are used to display the inspection information directly on the object. Once again, however, known systems tend to suffer from several drawbacks.
For example, PCT patent application No. WO2011/056196 teaches the use of a video-projector to display assembly related information on an object in a substantially undistorted manner during assembling steps. However, the video-projector of the device disclosed in the application is not configured to capture object data relative to the specific shape of the outer surface of the object being inspected or assembled. Consequently, the system disclosed in this application cannot be used to generate inspection information based on the acquired object data, such as portions of the outer surface of the object that are faulty or non-conforming with a reference, which is often valuable for operators in the inspection process.
PCT patent application No. WO2006/078684 and US patent application No. 2004/0189944 teach the use of a digitizer scanner to acquire a three dimensional profile of the object and a distinct laser projection device to project information onto it. As will be easily understood, the use of distinct devices for acquiring the three dimensional profile of the object and to project onto it requires the use of a calibration mean to calibrate both devices with respect to one another or with respect to the inspected object, in order for the distinct devices to work in combination. Moreover, such a system is not cost efficient as it duplicates the components included in the system. In addition, the laser projection device of known devices cannot project color information, can flicker due to the fact that the laser must sweep all the lines of the projected information, displays speckle and are not eye-safe.
In view of the above, there is a need for an improved three dimensional inspection system and corresponding method of operation, which would be able to overcome or at least minimize some of the above-discussed prior art concerns.